1. Technical Field
The present invention relates to a sheet material detection apparatus and a recording apparatus.
2. Related Art
A copying machine, a printer, and a fax machine are known as examples of a recording apparatus that records characters, images, or the like on various kinds of a sheet material such as paper, cloth, film, or the like. A sheet material detection apparatus that detects the passage of a sheet material is provided in such a recording apparatus. A lever member that turns when a sheet material is brought into contact therewith is provided on a sheet material transportation path. A detecting section detects the turn of the lever member, thereby detecting the passage of the sheet material. A sheet material detection apparatus that prevents the generation of noise due to the collision of a lever member with a stopper for stopping the movement of the lever member and chattering due to the mechanical vibration of the lever member is disclosed in JP-A-2007-031003. To prevent the noise and chattering, the apparatus is provided with a braking mechanism that reduces the speed of the lever member before it collides with the stopper.
The above sheet material detection apparatus of related art has the following problems. In recent recording apparatuses, a configuration for performing double-side printing on a sheet material to use resources efficiently or due to other reasons is adopted. To perform double-side printing, it is necessary to guide a sheet material into a turnover transportation path by transporting it in the direction opposite to the forward direction. However, since the lever member of the sheet material detection apparatus disclosed in JP-A-2007-031003 can turn in one direction only, specifically, the forward direction only, it cannot be used for detecting the passage of a sheet material when double-side printing is performed.
A stopper has to be removed if a configuration in which a lever member can turn toward both sides in the direction of transportation of a sheet material is adopted in order to detect the passage of the sheet material when double-side printing is performed. The removal of the stopper makes chattering caused by the lever member more likely to occur. To prevent chattering, the number of parts has to be increased. Moreover, in such a type of a sheet material detection apparatus, there is a possibility that a sheet material transported along a guide surface comes away from the guide surface and is raised depending on the position where the lever member is provided. The position of the lever member has to be determined carefully due to its influence on the transportation of a sheet material.